Metal cutting tools such as spot drills or pilot drills have a spot drill insert retained at the front of the drill, and possibly additional cutting inserts positioned alongside the spot drill insert. The spot drill insert may have multiple cutting areas, and it may be indexable for using a different cutting area when a used cutting area is worn or damaged.
The drill body has respective insert pockets adapted for receiving the spot drill insert and the additional cutting inserts, and retaining these inserts during machining operations. Cutting inserts and cutting tools as described above are shown, for example, in the following patent publications: DE19710996, EP1080812, U.S. Pat. No. 4,100,983, U.S. Pat. No. 5,259,707, U.S. Pat. No. 5,688,083, U.S. Pat. No. 5,505,569, U.S. Pat. No. 5,954,459, U.S. Pat. No. 7,108,460, US2004/124016, US2011/305534 and US2012/189393.
It is an object of the present invention to provide a novel indexable central drill insert with a plurality of lead drill portions and respective secondary cutting edges, and a tool holder with a central drill insert pocket suitable for receiving and firmly retaining the central drill insert.